I like having the rules well codified as a starting point- you are always going to have to make up something but it is best if you don't have to reinvent the wheel for every vehicle. In fact one issue I have within AM is that too often something gets made up for published material which doesn't mesh with something else that got made up for another bit of published material.
As to good and evil for D&D at least, I use the subjective, so evil people do good things for selfish reasons, and people who believe they are good justify evil deeds for good reasons, it's all messy in the middle, and on the edges the Blood war sums things up nicely- evil devils driven to extremes fighting evil demons.